let version = 0
type info_t = { version: int; id: string; title: string; people: string list; locations: string list }
type t = { info: info_t; fields: Msgpck.t; texts: Msgpck.t; peers: Msgpck.t }

let of_id id = Msgpck.of_string id
let to_id = Msgpck.to_string

let person p = Msgpck.String (Person.to_string p)
let persons ps = Msgpck.of_list @@ List.rev @@ Person.Set.fold (fun p a -> person p :: a) ps []

let str = Msgpck.of_string
let str_list ls = Msgpck.of_list @@ List.map str ls
let to_str_list x = List.map Msgpck.to_string
	(try Msgpck.to_list x with e -> prerr_endline "to_str_list"; raise e)

let of_set field t =
	List.rev @@ String_set.fold (fun s a -> Msgpck.String s :: a) (Text.set field t) []

let date = function "" -> Int32.zero | date -> Int32.of_int (Date.to_secs date)

let to_sec = function Msgpck.Int i -> Int32.of_int i | Msgpck.Uint32 i -> i | x -> Msgpck.to_uint32 x

let fields = Msgpck.(List [
	String "id"; String "time";  String "title"; String "authors"; String "topics";
	String "references"; String "replies";
	])
let to_fields fieldpack = List.map Msgpck.to_string (Msgpck.to_list fieldpack)

let to_info = function
	| Msgpck.List (v::id::n::a::ls::[]) ->
		let people = to_str_list a in
		let locations = to_str_list ls in
		Msgpck.({version = to_int v; id = to_string id; title = to_string n; people; locations})
	| _ -> invalid_arg "Pack header"

let of_info i = let open Msgpck in
	List [Int i.version; String i.id; String i.title; str_list i.people; str_list i.locations]

let of_text a t =
	let open Text in
	Msgpck.(List [
		of_id t.id;
		of_uint32 (date (Date.listing t.date));
		String t.title;
		persons t.authors;
		List (of_set "topics" t);
		List (of_set "references" t);
		List (of_set "in-reply-to" t);
	]) :: a

let of_text_list l = Msgpck.List l

let pack p = Msgpck.List [of_info p.info; p.fields; p.texts; p.peers]
let string p = Bytes.to_string @@ Msgpck.Bytes.to_string @@ pack p

let unpack = function
	| Msgpck.List (i::fields::texts::[]) ->
		Ok { info = to_info i; fields; texts; peers = Msgpck.List [] }
	| Msgpck.List (i::fields::texts::peers::[]) ->
		Ok { info = to_info i; fields; texts; peers }
	| _ -> Error "format mismatch"

let of_string s = unpack @@ snd @@ Msgpck.StringBuf.read s

let of_kv kv =
	let find k kv = try Store.KV.find k kv with Not_found -> "" in
	let find_ls k kv = try String_set.list_of_csv (Store.KV.find k kv) with Not_found -> [] in
	{
		info = { version = version; id = find "Id" kv; title = find "Title" kv;
			people = find_ls "Authors" kv; locations = find_ls "Locations" kv };
		fields;
		texts = Msgpck.List [];
		peers = str_list (find_ls "Peers" kv);
	}

let list filename = try
	let texts_list = function
	| Msgpck.List (_info :: _fields :: [texts]) -> Msgpck.to_list texts
	| _ -> prerr_endline "malformed feed"; [] in
	let _pos, data = Msgpck.StringBuf.read @@ File_store.to_string filename in
	Ok (texts_list data)
	with Not_found -> Error "unspecified export dir"

let contains text = function
	| Msgpck.List (id::_time::title::_authors::_topics::[]) ->
		(match to_id id with
		 | "" -> Printf.eprintf "Invalid id for %s" (Msgpck.to_string title); false
		 | id -> text.Text.id = id)
	| _ -> prerr_endline ("Invalid record pattern"); false

let numof_texts pack = List.length (Msgpck.to_list pack.texts)

let txt_iter_apply fn i = function
	| Msgpck.List (id::time::title::authors::topics::extra) ->
		let t = match time with Msgpck.Int i -> Int32.of_int i | Msgpck.Uint32 i -> i
			| x -> Msgpck.to_uint32 x in
		let id = to_id id in
		let title = Msgpck.to_string title in
		let topics = to_str_list topics in
		let authors = to_str_list authors in
		let references, replies =
			try begin match extra with [] -> [], []
			| refs::[] -> to_str_list refs, []
			| refs::replies::_xs -> to_str_list refs, to_str_list replies
			end with e -> prerr_endline "iter ref reps"; raise e
		in
		fn i id t title authors topics references replies
	| x -> Printf.eprintf "Invalid record structure: %s\n%!" (Msgpck.show x)

let txt_fold_apply fn i = function
	| Msgpck.List (id::time::title::authors::topics::extra) ->
		let t = match time with Msgpck.Int i -> Int32.of_int i | Msgpck.Uint32 i -> i
			| x -> Msgpck.to_uint32 x in
		let id = to_id id in
		let title = Msgpck.to_string title in
		let topics = to_str_list topics in
		let authors = to_str_list authors in
		let references, replies = begin match extra with
			| [] -> [], []
			| refs::[] -> to_str_list refs, []
			| refs::replies::_xs -> to_str_list refs, to_str_list replies
			end
		in
		fn i id t title authors topics references replies
	| x -> Printf.eprintf "Invalid record structure: %s\n%!" (Msgpck.show x); i

let iteri fn pack = List.iteri
	(txt_iter_apply fn)
	(Msgpck.to_list pack.texts)

let fold fn init pack = List.fold_left
	(fun acc m -> try txt_fold_apply fn acc m with Invalid_argument x -> prerr_endline x; acc) init
	(try Msgpck.to_list pack.texts with e -> prerr_string "Invalid pack.texts"; raise e)